Development of Environment-Friendly Microbial Nitrogen Fertilizer

August 6, 2026

Elucidation of the effects of a marine purple photosynthetic bacterium as a nitrogen fertilizer and its environmental burden

A joint research group from the RIKEN CSRS and Kyoto University has demonstrated that bacterial biomass derived from a marine purple photosynthetic bacterium effectively serves as an environmentally friendly organic nitrogen fertilizer in the current agricultural production system.

Global agriculture is facing immense pressure to meet the growing demand for food. While food supplies rely heavily on nitrogen fertilizers, conventional inorganic fertilizers cause numerous problems, including spills into the natural environment, greenhouse gas emissions, and soil degradation. Organic fertilizers have environmental advantages and release nitrogen slowly and stably. Existing animal- and plant-based fertilizers, however, are slow to mineralize because they have low nitrogen content (i.e., high C/N ratios), thereby producing large amounts of greenhouse gases (carbon dioxide, methane, and nitrous oxide [N₂O]) under specific conditions. Therefore, there is an urgent need for alternative fertilizers with sufficient fertilizing effects and small environmental burdens.

In this study, the research group conducted enzymatic kinetic analyses to examine bacterial biomass derived from the marine purple photosynthetic bacterium Rhodovulum sulfidophilum (R. sulfidophilum), demonstrating that the biomass releases nitrogen slowly and stably. Slow mineralization significantly reduces N₂O emissions compared with those from inorganic fertilizers. Experiments in broccoli fields showed that the bacterial biomass fertilizer produced by the research group maintained or improved the crop yields. This result demonstrated that the use of this biomass as nitrogen fertilizer is a promising strategy for the vegetable production with less greenhouse gas emissions. This is the first study to elucidate the mineralizing process of marine purple photosynthetic bacterial biomass applied to soil and its composite effects on N₂O generation.

These findings will hopefully help reduce greenhouse gas emissions from agricultural production and promote the domestic production of nitrogen fertilizers.

 

Original article

npj Sustainable Agriculture　DOI: 10.1038/s44264-026-00174-5

Shruthi, S. R. M. Yagi, D. D. Hanh, T. Maki, K. Ochiai, Y. Iwahashi, K. Murata, M. Shibata, H. Inoue, R. Nakano, T. Nakazaki, K. Numata,

"Effects of marine purple bacterial fertilizer on mineralization, nitrous oxide emissions and broccoli yield".

Contact

Keiji Numata
Team Director
Biomacromolecules Research Team